This invention relates to the field of high resolution engraving, and more particularly, to an engraving system and method which is capable of performing both cylindrical and helical engraving. The invention also has application to engraving systems using a high energy laser.
In such engraving an engraving stylus may be mounted on a carriage which is carried by a leadscrew along a path in engraving contact with the surface of a rotating cylinder such as a gravure printing cylinder. The leadscrew may be driven by a motor assembly which responds to electronic pulses and which rotates through a defined angular increment for each applied pulse. Either a stepping motor or a servomotor may be employed, and engraving may be performed. Circumferential systems rotate the leadscrew in stepped angular increments and do their engraving between steps, while the leadscrew is stopped. Helical systems drive the leadscrew more or less continuously without interrupting the engraving. Circumferential systems have the advantage of good vertical line reproduction and are less susceptible to patterns in engraving, due to no carriage movement during engraving, whereas helical systems are faster.
Data for controlling the engraving depth may be stored on a disk, tape or other storage medium and must be formatted to accommodate the particular engraving path which will be used. Once the data file has been prepared, the type of engraving path is dictated. If the data file has been prepared for circumferential engraving, it may not be used by a helical engraver, and vice versa. This has complicated production problems for large production facilities having both types of engravers. It has also limited smaller production facilities in their ability to accept data files originating at diverse locations. It is therefore seen that there has been a need for a versatile engraver able to accept data files prepared in either a circumferential or a helical format.